Background prior art relating to solar inverters and MPPT in general can be found in: EP0780750A; JP2000020150A; US2005/0068012; JP05003678A; GB2415841A; EP0947905A; WO2006/011071; EP1,235,339A; WO2004/006342; DE100 64 039A; US2005/030772; WO96/07130; U.S. Pat. Nos. 6,657,419; 2004/117676; 2006/232220; WO2004/001942; GB2419968A; U.S. Pat. Nos. 7,319,313; 7,450,401; 7,414,870; 7,064,967; “Cost-Effective Hundred-Year Life for Single-Phase Inverters and Rectifiers in Solar and LED Lighting Applications Based on Minimum Capacitance Requirements and a Ripple Power Port”, P. T. Kerin and R. S. Balog—technical paper; US2009/0097283; “Long-Lifetime Power Inverter for Photovoltaic AC Modules”, C. Rodriguez and G. A. J. Amaratunga, IEEE Trans IE, 55(7), 2008, p 2593; and US2008/097655.
We have previously described improved techniques for maximum power point tracking (MPPT) for solar invertors (see our UK patent application No. 1004621.7 filed 19 Mar. 2010 and U.S. Ser. No. 12/789,154 filed 27 May 2010). It has been recognised that these techniques facilitate the viable use of novel solar photovoltaic system architectures.